from __future__ import absolute_import

import logging
import time

from sentry.digests import get_option_key
from sentry.digests.backends.base import InvalidState
from sentry.digests.notifications import (
    build_digest,
    split_key,
)
from sentry.models import (
    Project,
    ProjectOption,
)
from sentry.tasks.base import instrumented_task

logger = logging.getLogger(__name__)


@instrumented_task(name='sentry.tasks.digests.schedule_digests', queue='digests.scheduling')
def schedule_digests():
    from sentry import digests

    deadline = time.time()

    # The maximum (but hopefully not typical) expected delay can be roughly
    # calculated by adding together the schedule interval, the # of shards *
    # schedule timeout (at least until these are able to be processed in
    # parallel), the expected duration of time an item spends waiting in the
    # queue to be processed for delivery and the expected duration of time an
    # item takes to be processed for delivery, so this timeout should be
    # relatively high to avoid requeueing items before they even had a chance
    # to be processed.
    timeout = 300
    digests.maintenance(deadline - timeout)

    for entry in digests.schedule(deadline):
        deliver_digest.delay(entry.key, entry.timestamp)


@instrumented_task(name='sentry.tasks.digests.deliver_digest', queue='digests.delivery')
def deliver_digest(key, schedule_timestamp=None):
    from sentry import digests

    try:
        plugin, project = split_key(key)
    except Project.DoesNotExist as error:
        logger.info('Cannot deliver digest %r due to error: %s', key, error)
        digests.delete(key)
        return

    minimum_delay = ProjectOption.objects.get_value(
        project, get_option_key(plugin.get_conf_key(), 'minimum_delay')
    )

    try:
        with digests.digest(key, minimum_delay=minimum_delay) as records:
            digest = build_digest(project, records)
    except InvalidState as error:
        logger.info('Skipped digest delivery: %s', error, exc_info=True)
        return

    if digest:
        plugin.notify_digest(project, digest)
